I Must
by fromidam
Summary: Featuring Rose Tyler/Billie Piper as the Doctor and Eleven/Matt Smith as the companion (John). While in the vortex a mysterious force takes control of the TARDIS, and the Doctor must protect herself and John while trying to figure out what's going on. AU.
1. Chapter 1

Note: The song _Halloween_ by Aqua really got me going on this story, and I used it for inspiration at the beginning.

* * *

The Doctor was working in the console room while John slept. The TARDIS was passing calmly through the vortex, the ambient light from the ceiling flickering occasionally as electrical charges that built up in the vortex passed through the TARDIS.

While they had been in a market the Doctor had spotted a replacement dial for the manual flight stabilizer, one that was closer to that of the original TARDIS console than the large and obtrusive crank handle she had had to repair it with when the original broke. She had just finished installing it and stepped back to see how the console looked with the change. She crossed her arms and scrunched her nose as she observed it - it didn't look right. Rather than make the controls look better, it just looked weird now in the midst of all the other odd bits she had used to fix the controls over the years.

The Doctor sighed and resigned herself to switching the components back, when all of a sudden the phone started to ring. She jumped, the TARDIS otherwise completely silent. She stared at the phone that sat on the other side of the console in shock. She thought back to the London Blitz and the gas mask child, which was the last (and only other) time the phone had rung. It ddring'ed again, and she tried not to think as she walked around to the other side of the console and picked up the phone gingerly, holding it up to her ear. She didn't say anything or make a sound, waiting for something to happen on the other end.

She was hoping that maybe she had imagined it, that maybe she needed another sleep cycle, when a grainy voice carried out of the speaker and into her ear.

"Remember me?" It sounded like a male voice, the Doctor didn't recognize it - and she had a very good memory.

"Sorry, you have the wrong number," she said.

"No I don't, Doctor," the voice said.

She paused in surprise before replying. "Alright, let's try this again. Hello, and who are you?"

"I'll tell you what I am, if you like." The Doctor stayed silent, waiting. "I'm coming to get you." The Doctor couldn't help but let out a huff of indignation. "You're in your TARDIS, aren't you?" it asked. She stayed silent, and then the mono-dimensional control handle sparked to her left. She turned her head to focus on it, and saw some of the controls start to turn and move on their own. Her eyes widened, and she opened her mouth to say something - she wasn't sure what - when the voice beat her to it. "Do you have one of your little pets with you?"

"JOHN!" the Doctor yelled, moving the phone away from her ear and covering the mouthpiece against her leg. When there was no answer in a couple of seconds she called her name again, slightly louder. "JOHN!" she could hear the panic in her voice the second time.

"What is it?" she heard John's voice over the double thump of her heartbeats. It was faint, being from another room, but it appeared that the TARDIS had moved his door closer to the console room so that he would hear her.

"YOU NEED TO GET OUT HERE NOW," she said, gripping the phone tighter in her hand, still pushing it against her leg.

"Alright, just give me a-"

"RIGHT NOW JOHN," she said, trying to make her seriousness clear in her voice.

A moment later a disgruntled John staggered out of the hallway that led to the rest of the TARDIS, looking very much like a colt in the way his limbs flailed about as he regained his balance. His flopped flat on one side, and he was dressed only in his goofy bow tie covered pyjama pants. His eyes met hers across the console room.

She raised the phone back to her ear, and she saw his eyebrows furrow when he realized that she was using the phone. "What do you want?"

"Always so concerned about your little pets," the voice said with a deep chuckle. "But neither of you can run from this."

The Doctor watched as the controls continued to move on their own, trying to analyze what they were trying to accomplish. "I'll ask you one more time: what. Do. You. Want?"

All of a sudden the console caught fire in front of her, and she jumped back away from the flames, the phone's cable extending to compensate. Sparks began to come out of some areas of the wall. She tried to pinpoint what wiring would be behind each spark, but the voice on the phone distracted her. "I want you to die." She heard a click as the voice hung up. A few moments later the cable melted and fell down to her side. She lowered the phone away from her head.

"Doctor?" John said from behind her. She turned her head to look at him. "What's going on?"

She looked down at the phone in her hand before dropping it on the floor, taking a step back from the console as the flames intensified. She squared her shoulders and looked up at him. "I don't know," she said, looking over her shoulder at the flaming console as her mind ran through all the possibilities she could think of. "Someone's controlling the TARDIS, somehow," she said. "But that's impossible. No, it's not. Time Lords - call them back - not this much control," she said, turning her head away from the flames that were slowly wicking away at what she had worked so hard to fix, her mind continuing to race.

"Doctor?"

"I'm thinking John, give me a minute," she said as she brushed her hair away from her face and ran her fingers through it.

"The hallway's moving."

"What are you talking about, it can't-" she started to say, but when she looked up at the back wall of the TARDIS she saw that John was right: the hallway was moving. Or rather, the wall was moving around the door frame, the circles moving from left to right as if the door wasn't there at all, causing it to look like it was the hallway moving. The Doctor turned in a circle, taking in every aspect of the room as she did so. Three-eighths of the way through her turn, she came to a startling conclusion, but she completed the turn to make sure.

The console room was shrinking.


	2. Chapter 2

**Previously:** _The console room was shrinking._

* * *

John seemed to notice at the same time that she did. "Doctor, maybe it's my imagination, but I the console room seems to be shrinking."

"It is," the Doctor said, her mind racing. They reached for each other's hand at the same time.

"Maybe we should get out of here," John said. "In case it keeps shrinking and squishes us."

"Have you been watching Star Wars?"

"Maybe."

The Doctor came to the conclusion that John had a valid point, and that being squished by a shrinking console room would definitely kill both of them. With a tug of her hand they're both off at a run towards the hallway leading out of the console room, John having to hop a little strangely as he was barefoot on the grating.

The hallway had no doors along the walls. Usually the TARDIS brought the doors that they needed to them when they were in a rush, but apparently that habit was being overridden by whatever was controlling the TARDIS.

"Where are the doors?" John asked from beside her. The Doctor had never explained how many aspects of the TARDIS's operation worked. She was about to start talking to stall while she tried to think of a solution, of a way to get control of the TARDIS away from whatever had taken it over, but when she turned her head to look at John she noticed something out of the corner of her eye.

Behind them she could still see part of the control room (which was still shrinking, she noted), but the view of it was getting ever-so-slightly narrower.

The hallway was shrinking as well – it was less noticeable than the shrinking of the console room, but she could still see it. John may not have noticed yet, she thinks, as it was still very subtle. But, she realized with a start, the speed could pick up at any moment.

Without even thinking she started to run again, John tripping slightly behind her, having not expected her to start moving right away. "Doct-"

"Not to scare you or anything John, but the hallway's shrinking too," the Doctor said, cutting him off.

"Oh. Well. What's the plan, then?" he asked from beside her, in step with her now.

"I'm working on it," she said, and she pulled them around a corner into a hallway that was slightly wider than the one they were in, but even before they entered it she could see that it was shrinking as well.

"Why aren't there any doors?" John asked again, since she hadn't answered him the first time.

"The TARDIS can move them around," she said as her mind raced, trying to come up with a fact that would spark a plan. "She usually moves the doors we need to wherever we are-"

"How?"

"Quad-dimensional rearrangement," she answered before continuing. "Whatever's controlling the TARDIS must have control over the location of all the rooms as well and is hiding them." They slowed slightly as they came to a four-way junction. She analyzed the width and rate of change of all the hallways and pulled them straight through, remaining in the path of the one they were in.

"So TARDISs don't have default layouts?" John asked, and she could tell that he was starting to feel out of breath. Her respiratory bypass hadn't kicked in yet, but she knew that it was only a matter of time. They wouldn't be able to keep going forever.

"No, the layout is generally influenced by the TARDIS's – and their Time Lord or Lady's – preferences."

"So there's no default? Nothing the TARDIS can't change?"

Default.

Default.

Default.

_Default_.

Zero.

They had just turned a corner, but she pulled them back the way they had come and pulled him through the hallway they had just passed. It was a fair bit narrower – they couldn't run side by side, but they kept their hands joined, John's stretched in front of him and the Doctor's out behind her – but she had a destination in mind this time.

"Doctor?"

"There is one room the TARDIS can't change, we're heading towards it now. Not far."

The hallway was shrinking faster than the others, but the turn off was just ahead of them. They squeezed into the next hallway which was blessedly wider; if they were walking they'd be able to walk side by side. It was shrinking fast, though. Maybe _it_ had picked up on her plan, but _it_ would have to be insanely powerful to do anything to their destination.

They entered an old area of the TARDIS, the walls still the plain off-white colour that some of her earlier forms preferred. She hadn't been in this section since then, so the TARDIS hadn't taken the time to align it with the current scheme. She didn't dwell on it, they had hit a slight curve in the corridor and she knew they were close.

The walls were closing in on them faster, but she could see the doorway just ahead. A thought came up that she didn't know if there was a lock on the door, but she was running sideways now and once they reached it she pushed her back against it and it swung open behind her, and she pulled John in with her. Before the door closed she saw that the hallway pulled back to its original width, but there was no way they were going back out there without a plan.


End file.
